The present invention relates to an image display apparatus such as a projector, a television and a monitor.
Such an image display apparatus is capable of receiving video signals having various resolutions (XGA, SXGA, UXGA, NTSC, PAL and a high-definition signal, etc.) output from personal computers and various video devices. The image display apparatus transforms the received video signal into a signal having a unique resolution displayable on its displaying part such as an LCD.
Further, the image display apparatus has a function of performing electronic zoom processing which includes partial expansion (enlargement) processing, display aspect ratio transformation processing and overscan display processing.
Moreover, there is an image display apparatus capable of receiving image data (file data) generated by an image pickup apparatus such as a digital camera and a video camera. Such an image display apparatus converts the received image data into a video signal, and supplies the video signal to its displaying part such that an image corresponding to the received image data is displayed thereon.
In a case where the received image data is compressed image data of JPEG format, MPEG format or others, the image display apparatus decompresses the compressed image data, converts the decompressed image data into the video signal, and then transforms resolution of the video signal to display resolution of the displaying part. In other words, even when the decompressed image data (video signal) has a high resolution (for example, QXGA), it is transformed into a low resolution such as XGA which is the display resolution of the displaying part for enabling display on the displaying part.
In such a case, the electronic zoom processing is performed on the video signal of the low resolution corresponding to the display resolution of the displaying part. Therefore, the electronic zoom processing makes the resolution of the image subjected to the electronic zoom processing (electronic zoom image) to be displayed extremely lower than the high resolution of the original image, which prevents a sufficient utilization of the original high resolution image data.
An image display apparatus disclosed in Japanese Patent Laid-Open No. 2006-303628 transforms, when performing multi-screen display, plural received signals whose resolutions are different from each other into signals having a same resolution (fixed low resolution) in a first resolution transforming part. Then, the apparatus transforms the fixed low resolution of each received signal into display resolution of its displaying part in a second resolution transforming part.
However, the image display apparatus disclosed in Japanese Patent Laid-Open No. 2006-303628 cannot suppress deterioration of the resolution of the image caused by the electronic zoom processing. This is because the electronic zoom processing is performed on the fixed low resolution video signal output from the first resolution transforming part.